Method and system for providing a nonvolatile logic array

Abstract

A method and system provide and program a nonvolatile logic device. The nonvolatile logic device includes input and output magnetic junctions and at least one magnetic junction between the input and output magnetic junctions. The input magnetic junction includes an input junction free layer having an input junction easy axis. The input magnetic junction may be switchable using a current driven through the magnetic junction. The output magnetic junction includes an output junction free layer having an output junction easy axis. Each of the magnetic junction(s) includes a free layer having an easy axis. The input magnetic junction is magnetically coupled to the output magnetic junction through the magnetic junction(s). In some aspects, the method includes switching the magnetic moment(s) of the input magnetic junction from a first state to a second state, applying and then removing magnetic field(s) along the hard axis of the at least one magnetic junction.

We claim: 
     
       1. A nonvolatile logic device comprising:
 an input magnetic junction including an input junction free layer having an input junction easy axis, the input magnetic junction being switchable using a current driven through the magnetic junction; 
 an output magnetic junction including an output junction free layer having an output junction easy axis; and 
 at least one magnetic junction between the input magnetic junction and the output magnetic junction, each of the at least one magnetic junction including a free layer having an easy axis, the input magnetic junction being magnetically coupled to the output magnetic junction through the at least one magnetic junction. 
 
     
     
       2. The nonvolatile logic device of  claim 1  wherein the input junction easy axis, the output junction easy axis and the easy axis are substantially parallel, each of the at least one magnetic junction further including a hard axis substantially perpendicular to the easy axis. 
     
     
       3. The nonvolatile logic device of  claim 1  wherein the input junction easy axis corresponds to an input junction shape anisotropy, the output junction easy axis corresponds to an output junction shape anisotropy, and the easy axis corresponds to a shape anisotropy for each of the at least one magnetic junction. 
     
     
       4. The nonvolatile logic device of  claim 1  wherein the input magnetic junction, the at least one magnetic junction, and the output magnetic junction form a linear array. 
     
     
       5. The nonvolatile logic device of  claim 1  wherein the at least one magnetic junction and the output magnetic junction form a linear array, the input junction being aligned with a first magnetic junction of the at least one magnetic junction in a direction substantially perpendicular to the linear array. 
     
     
       6. The nonvolatile logic device of  claim 1  wherein the input magnetic junction, the at least one magnetic junction, and the output magnetic junction share at least one layer. 
     
     
       7. The nonvolatile logic device of  claim 6  wherein the at least one layer includes a pinned layer. 
     
     
       8. The nonvolatile logic device of  claim 7  wherein the at least one layer includes a spacer layer. 
     
     
       9. The nonvolatile logic device of  claim 6  wherein the spacer layer includes a tunneling barrier layer. 
     
     
       10. The nonvolatile logic device of  claim 1  wherein the at least one magnetic junction and the output magnetic junction have a plurality of magnetic anisotropies decreasing monotonically from the input magnetic junction to the output magnetic junction. 
     
     
       11. The nonvolatile logic device of  claim 10  wherein the at least one magnetic junction and the output magnetic junction have a plurality of shape anisotropies corresponding to the plurality of magnetic anisotropies. 
     
     
       12. The nonvolatile logic device of  claim 11  wherein each of the at least one magnetic junction has a length and a width, the length decreasing from the input magnetic junction to the output magnetic junction. 
     
     
       13. The nonvolatile logic device of  claim 11  wherein each of the at least one magnetic junction has a length and a width, the width increasing from the input magnetic junction to the output magnetic junction. 
     
     
       14. The nonvolatile logic device of  claim 10  further comprising:
 a plurality of current lines corresponding to the input magnetic junction, the at least one magnetic junction, and the output magnetic junction, the plurality of current lines corresponding to the plurality of magnetic anisotropies. 
 
     
     
       15. The nonvolatile logic device of  claim 14  wherein each of the plurality of current lines is configured to drive a current corresponding to a magnetic anisotropy of the plurality of magnetic anisotropies. 
     
     
       16. The nonvolatile logic device of  claim 14  wherein each of the plurality of current lines is configured to start driving the current at a time corresponding to the magnetic anisotropy of the plurality of magnetic anisotropies. 
     
     
       17. The nonvolatile logic device of  claim 14  wherein at least a portion of the plurality of current lines includes a primary current conducting portion and a cladding surrounding at least a portion of the primary conducting portion. 
     
     
       18. A method for providing a nonvolatile logic device comprising:
 providing an input magnetic junction including an input junction free layer having an input junction easy axis; 
 providing an output magnetic junction including an output junction free layer having an output junction easy axis; and 
 providing at least one magnetic junction between the input magnetic junction and the output magnetic junction, each of the at least one magnetic junction including a free layer having an easy axis, the input junction easy axis, the output junction easy axis, and the easy axis being substantially parallel, the input magnetic junction being magnetically coupled to the output magnetic junction through the at least one magnetic junction. 
 
     
     
       19. The method of  claim 18  wherein the input junction easy axis, the output junction easy axis and the easy axis are substantially parallel, each of the at least one magnetic junction further including a hard axis substantially perpendicular to the easy axis. 
     
     
       20. The method of  claim 18  wherein the input magnetic junction, the at least one magnetic junction, and the output magnetic junction form a linear array. 
     
     
       21. The method of  claim 18  wherein the at least one magnetic junction and the output magnetic junction form a linear array, the input junction being aligned with a first magnetic junction of the at least one magnetic junction in a direction substantially perpendicular to the linear array. 
     
     
       22. The method of  claim 18  wherein the input magnetic junction, the at least one magnetic junction, and the output magnetic junction share at least one layer. 
     
     
       23. The method of  claim 18  wherein the at least one magnetic junction and the output magnetic junction have a plurality of magnetic anisotropies decreasing monotonically from the input magnetic junction to the output magnetic junction. 
     
     
       24. The method of  claim 18  wherein the input magnetic junction is switchable using a spin transfer current driven through the input magnetic junction. 
     
     
       25. The method of  claim 18  wherein the input magnetic junction is switchable due to an external magnetic field. 
     
     
       26. A method for programming a nonvolatile logic device including an input magnetic junction, an output magnetic junction and at least one magnetic junction between the input magnetic junction and the output magnetic junction, the input junction having an input junction easy axis, the output junction having an output junction easy axis, each of the at least one magnetic junction including a free layer having an easy axis and a hard axis, the input junction easy axis, the output junction easy axis, and the easy axis being substantially parallel, the input magnetic junction being magnetically coupled to the output magnetic junction through the at least one magnetic junction, the comprising:
 switching at least one magnetic moment of the input magnetic junction from a first state to a second state; 
 applying at least one magnetic field along the hard axis of the at least one magnetic junction; and 
 removing the magnetic field. 
 
     
     
       27. The method of  claim 26  wherein the step of switching the at least one magnetic moment of the input magnetic junction further includes:
 driving a current through the input magnetic junction in a perpendicular-to-plane orientation. 
 
     
     
       28. The method of  claim 27  wherein the step of switching the at least one magnetic moment of the input magnetic junction further includes switching the input magnetic junction using spin transfer. 
     
     
       29. The method of  claim 26  wherein the hard axis is perpendicular to the easy axis. 
     
     
       30. The method of  claim 26  wherein the easy axis is substantially parallel to the input junction easy axis and the output junction easy axis.